1. Field of the Invention
The present invention relates generally to an improved concentric tube ozonator which is designed from theoretical considerations to produce ozone efficiently with minimum electrical power consumption. More particularly, the subject invention pertains to an improved and relatively simple ozonator design as described wherein concentric tube assemblies in the ozonator are designed for ease of construction and replacement of the components thereof, with the concentric tube assemblies providing for the relatively precise positioning of the components therein, as is required for proper and efficient operation of the ozonator.
2. Discussion on of the Prior Art
Van Tuyle U.S. Pat. No. 3,214,364 is of interest to the present invention by disclosing a prior art commercial ozonator design. An outer metal tube constitutes one electrode and encloses a glass tube which is the dielectric of the ozonator. The outside diameter of the glass tube is somewhat smaller than the inside diameter of the metal tube, thus providing an annular space through which the gases being ozonized pass. An inner electrode is positioned within the dielectric glass tube, and is formed of a perforated member such as a grid or screen which is spaced from the inner surface of the dielectric tube. The glass tube employed is one having a wall thickness of not over about 2.25 mm and is described as being as thin as manufacturing techniques will permit, with a practical lower limit being about 1.5 mm Moreover, the glass tube, instead of being closed at one or both ends, is left open at the gas entrant end, while the opposite end is provided with a restricting device arranged to permit only a predetermined portion of the entrant feed gases (of the order of 30-70% thereof) to pass through the tube in contact with the perforate member comprising the inner electrode. The balance of the gases pass through the annular space between the outer metal tube and the inner glass tube. The diameters of the tubes are so selected that the width of the annular space therebetween is held below about 2.5 mm and preferably below about 2 mm, with a practical lower limit being giving as about 1 mm. Accordingly, this prior art approach discloses and teaches much larger annular discharge gaps than the present invention, and moreover the design is more complex than that of the present invention and involves a grid or screen inner electrode.
Harter et al U.S. Pat. No. 4,049,707 is also of interest to the present invention, and discloses an ozonator design having a first flat plate electrode, a composite mica glass dielectric structure located along the side of and spaced from the first plate electrode so as to define a gap between the first electrode and the dielectric structure, and a second flat plate electrode. The gap is closed off by a flexible seal permitting the thickness of the gap to be adjusted, preferably in relation to the operating parameters of the equipment used to power the apparatus and to the characteristics of the product or products produced. In actual practice, ozonator designs having flat plate electrodes and dielectrics similar to the Harter et al patent have proven to be rather difficult to adjust and maintain in proper operation. However, this patent is of particular interest in disclosing that the flat discharge gap of the ozonator should be between 0.25 and 0.50 mm to maximize ozone product efficiency.
Tanaka et al U.S. Pat. No. 4,232,229 is also of interest to the present invention, and discloses a tubular ozonator design which includes a pair of spaced tubular electrodes including a ground electrode and a high voltage electrode, and a tubular dielectric substrate disposed between the ground electrode and the high voltage electrode. A perforated metal substrate is placed in the gap space between the ground electrode and the dielectric substrate, and a first spacer is placed between the perforated metal substrate and the dielectric substrate for maintaining a constant separation gap therebetween. A second spacer is disposed between the perforated metal substrate and the grounding electrode to maintain the perforated metal substrate in proper position between the dielectric substrate and the grounding electrode, wherein a uniform separation distance promoting a uniform electrical discharge is maintained between the perforated metal substrate and the dielectric substrate by the first and second spacers. This patent is of particular interest in disclosing a preferred discharge gap of 0.5 mm. However, this particular ozonator design is relatively inefficient in several respects when compared to the present invention. The design is such as to present only a single annular discharge gap, rather than the more efficient dual annular discharge gaps of the present invention, and moreover requires a perforated metal net spacer in the middle of the discharge gap.